Piezoelectric material is commonly used in vibration energy harvesting devices. To gain an optimal power or voltage output, piezoelectric material is usually applied on top of a mechanical vibration structure where the stress is most concentrated. Most of the state-of-the-art piezoelectric harvesters use one piece continuous piezoelectric material to serve this purpose. However, as the vibration intensity and modes vary, the stress-concentrated area can vary in location and size. Since the piezoelectric material layout cannot be adjusted accordingly, the harvester efficiency and power output will be compromised when the vibration deviates from the design target.